Tom Kimball's long and winding path from faith to doubt began shortly before he got married. But he was young then, and he assumed that what he now calls his "low-level" doubts would just go away. Meanwhile, Page Kimball assumed she was marrying not only an Eagle Scout and a returned missionary but a man whose faith was unshakable.

It's not like a person wakes up one morning and decides, "Today I'll start doubting," Tom says. But there it was: Things just didn't make sense anymore. And once he started questioning one thing it seemed like it opened the door to yet another uncertainty.

What he wanted to do was talk about his doubts with Page. But those questions at first annoyed her, then angered her, and then frightened her. She didn't understand, she explains now, "why he didn't love me enough to just believe."

If a couple marries, knowing that one person is a believer and one isn't, that's one thing, says Salt Lake therapist Marybeth Raynes. At least there's forewarning, even if deep down the believer hopes that the non-believer will change. But when the spiritual ground starts to shift in a marriage right under a couple's feet, that's a lot more wrenching, she says.

Sometimes one spouse will become less religious. Or more religious. Sometimes there will be differences about specific dogma, or sometime one spouse will begin to doubt the existence of God. The most lethal mix, says Raynes, is when one spouse is still a believer and the other becomes bitter about religion. Sometimes the sense of betrayal, the sense that a religion isn't true after all, becomes the lens through which the person views everything else in life, "the focal point of other disappointments," Raynes says.

Often, says Grace Baptist Church's Rev. Pat Edwards, it's a "crisis scenario" that causes one spouse (or sometimes both) to falter in faith. "Oftentimes it's the loss of a child or a sibling. People say, if there was really a God, he wouldn't allow this suffering to take place." In a crisis like that, the Rev. Edwards says, "what happens is that very few people stay where they're at. They either go closer to God or question God or deny God."

When one spouse begins to doubt, "the other spouse feels a tremendous loss," he says. "Suddenly not only has there been this crisis, but now there's no longer this shared resource they can go to."

But it's not always a crisis that pushes someone toward doubt or inactivity. One of the Rev. Edwards' parishioners recalls a time a decade ago when she began "veering" — started putting God on hold, she says. "It wasn't so much a mental process of 'does God exist?' but a compartmentalizing. ... There was a Sunday me and a Monday me."

Her husband stuck with her, she says. "He prayed fervently for me. He just hung in there. And I think his faith was strengthened during that experience. He had to hang on more to God order to survive it."

The collision of faith and doubt in a marriage is prevalent enough to have spawned a collection of self-help books with titles like "When He Doesn't Believe: Help and Encouragement for Women Who Feel Alone in Their Faith," "Beloved Unbeliever" and "Spiritually Single: Living with an Unbelieving Husband."

Some religions discourage couples from marrying if they don't share the same beliefs. "The word of God says that two should not be 'unequally yoked together,"' says Pastor Jim Ayers of Valley Assembly of God, quoting Second Corinthians. "With all the problems in life, to add a faith issue, where one maybe doesn't even believe in God or is indifferent at best" just adds another burden, says the Rev. Ayers.

But if a couple is already married and one spouse "steps away" from religion, he says, "the believer is to remain with the unbeliever." He cites First Corinthians: "For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband."

Sometimes a marriage is knocked off-kilter when one spouse becomes more religious. One Layton woman says that now that she has started attending church "there's a part where we just don't relate and at times it's really hard." On Sundays, she and the children go to worship and her husband goes to Barnes & Noble.

Her husband has told her, "Don't have any expectations" that he will become involved with the family's religious life. Sometimes he'll stay after church for the congregational pancake breakfast — "If that's a step, it's a step," the wife says. "If that's as far as he wants to go, I have to be OK with it."

As her pastor says: "It's not up to you to bring that person back into the fold, it's up to God. Just pray and be a good person."

In Troy Bowles' marriage, his wife became more active in The Church of Jesus Christ of Latter-day Saints after their children were born. Bowles himself is an agnostic who grew up in a polygamous household. Now a philosophy major at the University of Utah and getting a divorce, Bowles says that as his wife got more religious he started to feel "more isolated and lonely."

Even if couples share a faith but differ on specific dogma — "Should we tithe on gross or net? What's legitimate to do on Sunday?"— that can cause huge rifts, too, says therapist Raynes. Couples who have trouble communicating, whose first impulse is to fight, will do it around any issue, she says.

What works best for a marriage, she says, is "if each spouse can really see the other's position and respect it, and not go into a regressed state of blame and threats." In a case where one spouse's position about faith changes, she says, both spouses can be in "deep anguish."

What helps is for each spouse to "return to why do you love each other," Raynes says, "to notice all the good things in the relationship."

When one Salt Lake wife faced her husband's drifting faith — he started drinking coffee and no longer believed the literalness of his church's theology — a friend suggested she get a divorce. "And I said, 'for that?"' She worries how far her husband's doubts will take him, "but I'm so in love with him, what can I do?" she says.

In the end, Page Kimball also decided that her marriage came first, as she explained recently at a Sunstone Symposium panel called "For Better, For Worse, For Apostasy?"

Tom Kimball thinks of himself as a Stage Four in the hierarchy of faith development delineated by Emory University professor James Fowler. As Kimball explains it, Stage 4 is when "you find loose ends (in your religion) and as you try to put them back together you find more, and you feel betrayed."

When Tom first started questioning his Mormon religion and his faith in God, he and Page spent quite a few years not talking about it. It was just too painful, Page says. "I felt so threatened." Because her religion believes in eternal marriage, the stakes were especially high. And praying together about Tom's doubts was out of the question.

In the end, Page says, "I stopped looking at him through the church's eyes. I stopped trying to make him what I thought he should be, that vision of what a husband and priesthood holder should be. I just had to let that go and look at him for the wonderful person he is."

Her decision to love and accept Tom improved their marriage, she says, but "his doubts opened a door for mine." For a while, she began looking at other religions. For his part, Tom has decided to stay connected to his culture and his church. He remains "70 percent active," and attends Elders Quorum each Sunday, where he finds that the other men have gone out of their way to make him feel wanted, even though they know he has reservations about Mormon history and theology. Now Page is back at the ward, too.

Their relationship with religion, and their ability to find a spirituality they can share, is a work in progress. Meanwhile, Tom has a certainty about doubt: it's "how you become a mature person and build a mature faith."